Generation-excitation mechanism in bismuth-vapor laser

Abstract

The laser based on a self-limited transition of the bismuth atom ([lambda] = 472.2 nm, 7S[sup 4]P[sub 1/2] [yields] 6p[sup 3] [sup 2]D[sub 3/2][sup 0] transition) is of interest primarily by having a number of interesting features from the physical standpoint. The most important is that as a rule the lasing zone is adjacent to the inner surface of the gas-discharge tube. In addition, the bismuth-vapor lasing pulse-repetition frequency has a lower cutoff limit. These two features are unique for atomic lasers with self-limited transitions. The temperature interval in which lasing is achieved is also unusually narrow. All these features have found no unambiguous incontrovertible explanation from a single viewpoint. Investigations of the relaxation of the lower working level in the interval between the pulses have likewise added significantly to the understanding of the question. In this situation, after analyzing the results of studies by G.G. Petrash and co-workers as well as their own study, in which lasing from the entire volume of the gas-discharge tube was obtained at a neon buffer-gas pressure 1-5 torr, they have concluded that a thorough study is necessary of the role of the Bi[sub 2] dimers in the active medium of the Bi laser.